Hydraulic valvetrain lash adjusters are known for compensating for wear or growth between various parts of the valvetrain. U.S. Pat. No. 5,107,806 to Dohring et al. is an example of an automatic hydraulic valve-clearance compensating element in which a pair of piston elements are relatively moveable to provide for extension or contraction between the parts.
In many cases, the lash adjusting unit, if contained within a rocker arm, is located at the end of the rocker arm opposite the end containing the pivot shaft. This is a disadvantage because the farther the assembly is from the pivot shaft, the greater the moment of inertia of the lash adjusting mass, which results in greater stress on the parts and parasitic losses in the engine.
Valve deactivators are also known for disabling the movement of one or more of the valves of the engine during low power or torque periods, for economy purposes. The known devices, however, are generally complicated and costly, having many parts, and often require, for example, splitting the camshaft or crankshaft or declutching the rocker arm to render it inoperative to move the valve stem.
The invention provides a simplified construction of a single rocker arm that encloses both a hydraulic lash adjuster as well as a valve deactivator, integrated in a manner to minimize the rotational moment of inertia of the mass of the rocker arm.